Show HN: StemJSON – a language for LLMs to extend native mobile apps on the fly

Push complete functional modules from your backend - state, actions, expressions, navigation, validation - straight to the device.

your server → StemJSON → device

From a prompt or a Figma export to a runnable native prototype. Tools emit StemJSON; the runtime renders it on-device - no glue code in between.

Figma / AI tool → StemJSON → runnable app

Drop StemJSON modules into a native app for the parts that change often - settings, onboarding, content feeds - and keep the rest hand-written.

StemJSON modules + native code → one app